Donald Trump and Hillary Clinton remained the front-runners in the quest for the White House, but Senators Ted Cruz and Bernie Sanders scored key victories in the latest contests.

Republican Trump and Democrat Clinton both won in the delegate-rich state of Louisiana on Saturday, keeping them on top at a critical point in the US presidential race.

Results from votes in five states were split, but one element was clear: Republican Cruz boosted his claim as the most viable alternative to Trump after taking Kansas and Maine and put poorly performing Senator Marco Rubio under immense pressure to turn his campaign around or bow out.